Expert: Will Creed - 10/31/2004

Question
Hello:

I was wondering if you might be able to tell of any ways to prevent fluoride burn in my corn plants.  I've alway had this problem with these plants, it starts out with just brownish leaf tips and then the leaf yellows from the tip up.  I've tried various amounts of water, keep humidity at at least 50% and keep the plants in bright filtered light.  

I've been reading about the affects of fluoride on some dracaenas and I think that this may be the problem.  I've checked with my local water authority on the amount of fluoride in our water system and they informed me that levels are generally between 0.8 and 1.2 mg/L of fluoride.  I also re-read the labeling on the packaging of the potting soil I have the plants in and it contains perlite.  I've read in different sources that perlite may also contains fluoride.  Not sure if this is true or not.  

Anyway, I love the architecural appearance of cornplants and want them to be healthy as possible, any suggestions on getting rid of these distracting brown and yellow leaves?

Thanks!

-Jonathan  

Answer
Hi Jonathan,

Although other Dracaena species are quite senstive to fluoride, Dracaena massangeana (corn plant) is only slightly sensitive. I care for many corn plants here in NYC and use fluoridated water without a problem.

I suspect the symptoms you have described are caused by excess soil salts - from using hard water or from over fertilizing - or from letting the soil become too dry.

If your local tap water is on the hard side, then switch to distilled, filtered or rainwater. If you are fertilizing regularly, stop because corn plants use very little nutrients.

Although corn plants do not like constantly soggy soil, if the soil gets too dry, then the minerals concentrate in the soil and cause tip burn. Water thoroughly when the top quarter of the rootball feels dry.

If you still suspect that fluoride is the problem, then make sure the soil pH is in the 6.0 to 6.8 range. Fluoride is insoluble within that pH range.

Perlite and superphosphate fertilizers are sources of fluoride. A normal amount of perlite should not pose a problem, especially if the pH is in the proper range. Do not use fertilzers that contain superphosphate.

Please let me know if any of this is unclear or if you have any additional questions.

Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: wcreed@HorticulturalHelp.com

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